Why do doctors always look in your eyes? It seems like whatever you go in for - a fever, a headache, high blood pressure - they need to peek in the peepers. Well, just as the eyes are your window to the world, they're our window to blood vessels. The blood vessels in the retina are the only ones in the body that can be viewed directly. It's like we can look straight through the skin and watch disease processes do their damage.
With hypertension, a fundoscopic exam (eye exam) is especially useful thanks to a whole spectrum of symptoms that can tell us about the progression of this widespread medical condition. AV nicking shows venous damage around intersections with hypertensive arteries. Cotton wool spots are tiny infarcts of retinal tissue due to blood vessels pinching off parts of nerve cells. Finally, the retina can hemorrhage causing tiny blobs of blood to escape the vasculature. These can be tiny and unnoticed (until a doctor sees them during an eye exam) or so large that they severely reduce the persons vision.
TIL: Stages of heart failure were recently renamed so that stage A heart failure is really just a warning of predisposing risk factors. Stage A means you don't actually have any symptoms or structural damage, but have one or more of the high risk warning signs that, if left untreated, are likely to cause the other, more legitimate stages of heart failure.
Pulsus alternans is an interesting, if ominous, effect of left systolic heart failure whereby the heart alternates strong and weak beats thanks to a poorly executed compensatory response. When the heart fails to pump out enough blood, some blood is left in the ventricular chamber. When the heart tries to refill that chamber, it now overfills it because of the leftovers from the previous beat. This stretches the muscle out (using the Frank-Starling mechanism) causing the heart to beat harder. This tuckers out the already failing heart and it pumps rather feebly the next time, starting the cycle over again.
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